Minimally invasive treatment of vertebra (mitv) using a calcium phosphate combination bone cement

ABSTRACT

Featured are a biocompatible, injectable, self-setting, cohesive, bone-bonding and remodeling calcium phosphate composite material and its use in methods of repairing defective bone, e.g., in vertebroplasty augmentation and kyphoplasty.

BACKGROUND OF THE INVENTION

Naturally occurring bone is contains about 70% mineral (nanometer-sizedcalcium deficiency hydroxyapatite) and about 30% organic matrix(collagen, proteins etc.). Bone loss occurs as results of increased bonedestruction (resorption by osteoclastic activity) relative to boneformation (by aging or disease). Both bone resorption and formationoccur continuously in the skeleton as part of normal skeletal function.During this process packs of bone are being destroyed and rebuilt in aprocess called remodeling.

Osteoporosis is a disease characterized by low bone mass leading to anincreased frequency of low energy fractures. It is known thatosteoporosis is a condition that features loss of the normal density ofbone and fragile bone. It leads to literally abnormally porous bone thatis more compressible (e.g., spongy) than dense (e.g., brick). Thisdisorder of the skeleton weakens the bone, which leads to an increase inthe risk of breaking bones (bone fracture).

Bones that are affected by osteoporosis can fracture with only a minorfall or injury that normally would not cause a bone fracture. Thefracture can be in the form of cracking (as in a hip fracture), orcollapsing (as in a compression fracture of the vertebrae of the spine).The spine, hips, and wrists are common areas of osteoporosis-relatedbone fractures, although osteoporosis-related fractures can also occurin almost any skeletal bone area.

Among fractures encountered in osteoporosis, vertebral fractures must betaken into account because they are frequent (about 16% ofpostmenopausal women) and lead to back pain, disability and decreasedheight.

Bisphosphonates, which are analogues of naturally occurringpyrophosphate that contain a carbon instead of an oxygen atom, arewidely used in the treatment of osteoporosis in order to inhibitosteoclastic bone resorption. Bisphosphonates have been observed topreferentially bind to bone mineral in areas that are activelyundergoing remodeling. After desorption in bone, bisphosphonates areliberated again only when the bone is resorbed (by osteoclasts). Themost common adverse event with bisphosphonate treatment isgastrointestinal disturbance, including, e.g., pain, diarrhea, andabdominal discomfort. Given that treatment for osteoporosis is typicallylong term, compliance and tolerability (without side effect) areimportant.

Despite the fact that traditional approaches (mostly based onnon-surgical therapies as a preventive measure) have been shown to beineffective in alleviating pain and correcting spinal deformity, theminimally invasive treatment of vertebral compression fracture (VCF)remains under-developed. Currently, vertebroplasty is performed bypercutaneously injecting (by minimally invasive surgery (MIS)) a bonesubstitute material (BSM) into the vertebral bodies under fluoroscopicand/or computed tomography guidance. A related treatment, kyphoplasty,includes an attempt to expand the vertebra with an inflatable balloonprior to the injection of a BSM. Kyphoplasty is an effective treatmentfor painful osteoporotic compression fractures, however, patients whoundergo kyphoplasty procedure should be informed of the significant riskof adjacent-level fractures over the next 60 days. The reason for thisassociation is unclear, but may occur because cement augmentation at onevertebral level places further stress on adjacent levels.

Typically, a MIS technique allows for the same outcomes as conventional(open) surgery, but with additional benefits that include, e.g., theavoidance of open invasive surgery in favor of closed (tiny incision) orlocal surgery, a reduction in surgical complications (muscle stripping,blood loss, etc.), a reduction in operative trauma (by soft tissuepreservation) with less postoperative pain, a reduction in patienthospitalization time and, consequently, a significant reduction incosts, an increase in the speed of functional return to dailyactivities, a shorter recovery time (a few months instead of a year),and a few cosmetically tiny scars rather than one large scar.

There are an estimated 800,000 vertebral fractures from osteoporosisevery year according to the U.S. National Osteoporosis Foundation, andabout 200,000 of these are treated surgically. The vertebrae compressionfracture market is estimated at $160 million (in 2007) with thepotential to reach $750 million as surgery continues to grow as thestandard of care for the condition. In 2004, the global market forminimally invasive VCF treatments, including Kyphoplasty andPercutaneous Vertebroplasty (PV), was valued at more than $250 million.

The current product in today's market used for vertebroplasty indicationis a decades-old, non-bioresorbable, and non-remodelingpolymethylmethacrylate (PMMA) cement, which is injected in the vertebralbody for pain relief and to strengthen weakened vertebral bone. PMMAcement is remarkably strong and does not deteriorate over time, yet italso does not integrate into bone. Moreover, the high compressionstrength of PMMA can cause adjacent vertebral body fractures by exertinghigh non-compliant forces on the adjacent occurring adjacent fractures.

In 2007, Health Canada issued information related to seriouscomplications associated with the use of PMMA cement in vertebroplastyand kyphoplasty procedures. Among these complications are the following:death due to sudden blood pressure drop that may be related to therelease of the PMMA monomer (leaching effect) into the vascular system,PMMA extravasations into the spinal canal leading to neurologic deficit,with compression of the spinal cord and/or nerve roots, new fractures,usually of adjacent non-augmented vertebrae, and pulmonary embolism dueto PMMA.

Unlike PMMA, calcium phosphate cement (CPC), when delivered into thebone, is acted upon by osteoblasts and osteoclasts in the residualtrabecular bone and can be remodeled into bone. With its lowercompressive strength, CPC also causes less stiffness of the vertebralbody. CPC can also integrate into the trabecular bone structure and canpromote bone restoration.

There exists a need for compositions that can be used in kyphoplasty andvertebroplasty applications that avoid the complications associated withPMMA cement compositions.

SUMMARY OF THE INVENTION

The invention features a biocompatible, injectable, self-setting,cohesive, bone-bonding and remodeling calcium phosphate (CaP) compositematerial and its use in methods for vertebroplasty augmentation. Inpreferred embodiments, the CaP material is a nanocrystalline apatite(NCA) or a nano-low crystalline apatite (NLCA), which can be synthesizedusing, e.g., a low temperature double decomposition technique or a highenergy grinding technique. The CaP material of the present invention mayalso include polymers or other chemical bonding agents, such aspolylactic acid (PLA) and hydroxyethyl methacrylate (HEMA) monomers.Unlike PMMA-containing cements, the CaP materials of the presentinvention can be remodeled in vivo and do not contain volatile monomersthat can be “leached” into the body of a patient.

In a first aspect, the invention features a method for performingvertebroplasty on a vertebral body by injecting (e.g., through a 16gauge needle or less, e.g., an 11 gauge needle) a flowable bone cementinto at least one vertebral body (e.g., by directly injecting into thevertebral body or by injecting into the vertebral body after creating acavity) of a mammal (e.g., a human or a non-human mammal) and allowingthe flowable bone cement to harden. The flowable bone cement includes acalcium phosphate material (e.g., a nanocrystalline apatitic calciumphosphate, such as a NCA and a NLCA), a radio-opaque agent, and apharmaceutically acceptable fluid in an amount sufficient to produce theflowable bone cement. The calcium phosphate can be selected fromamorphous calcium phosphate, poorly crystalline calcium phosphate,hydroxyapatite, carbonated apatite (calcium-deficient hydroxyapatite),monocalcium phosphate, calcium metaphosphate, heptacalcium phosphate,dicalcium phosphate dihydrate, tetracalcium phosphate, octacalciumphosphate, calcium pyrophosphate, and tricalcium phosphate, or mixturesthereof. When hardened, the flowable bone cement has a compressivestrength of 1 mPa or greater and is resorbable in vivo. In anembodiment, the flowable bone cement further includes one or more of atleast one agent that promotes bone growth or inhibits bone resorption,demineralized bone matrix, and one or more crystal growth inhibitors, oris formed using one or more of benzoyl peroxide powder, hydroxyethylmethacrylate (HEMA), and dimethyl-ρ-toluidine. In other embodiments, thecalcium phosphate material is chemically bonded using a polymer (e.g.,polylactic acid) or other chemical bonding agent (e.g., HEMA).

In other embodiments, the flowable bone cement further includes acohesiveness agent, an osteogenic agent, or a medicinal agent. Thecohesiveness agent can be selected from the group consisting of:

a) one or more polymers selected from polysaccharides, nucleic acids,carbohydrates, proteins, polypeptides, poly(α-hydroxy acids),poly(lactones), poly(amino acids), poly(anhydrides), poly(orthoesters),poly(anhydride-co-imides), poly(orthocarbonates), poly(α-hydroxyalkanoates), poly(dioxanones), poly(phosphoesters), poly(L-lactide)(PLLA), poly(D,L-lactide) (PDLLA), polyglycolide (PGA),poly(lactide-co-glycolide (PLGA), poly(L-lactide-co-D, L-lactide),poly(D,L-lactide-co-trimethylene carbonate), polyhydroxybutyrate (PHB),poly(ε-caprolactone), poly(δ-valerolactone), poly(γ-butyrolactone),poly(caprolactone), polyacrylic acid, polycarboxylic acid,poly(allylamine hydrochloride), poly(diallyldimethylammonium chloride),poly(ethyleneimine), polypropylene fumarate, polyvinyl alcohol,polyvinylpyrrolidone, polyethylene, polymethylmethacrylate, carbonfibers, poly(ethylene glycol), poly(ethylene oxide), poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof;

b) a homo- or co-polymer having one or more monomers selected from thegroup consisting of acrolein potassium, (meth)acrylamides, (meth)acrylicacid and salts thereof, (meth)acrylates, acrylonitrile, ethylene,ethylene glycol, ethyleneimine, ethyleneoxide, styrene sulfonate, vinylacetate, vinyl alcohol, vinyl chloride, and vinylpyrrolidone);

c) a polyphenolic complexing agent selected from gallotannins,ellagitannins, taragallotannins, caffetannins, proanthocyanidins,catechin, epicatechin, chlorogenic acid, and arbutin; or

d) an agent selected from alginic acid, arabic gum, guar gum, xanthamgum, gelatin, chitin, chitosan, chitosan acetate, chitosan lactate,chondroitin sulfate, N,O-carboxymethyl chitosan, a dextran, fibrin glue,glycerol, hyaluronic acid, sodium hyaluronate, a cellulose, aglucosamine, a proteoglycan, a starch, lactic acid, a pluronic, sodiumglycerophosphate, collagen, glycogen, a keratin, silk, and mixturesthereof.

In other embodiments of the first aspect of the invention, theosteogenic agent is selected from the group consisting of transforminggrowth factors-beta (TGF-β), activins, inhibins, and bone morphogeneticproteins (BMPs), while the medicinal agent is selected from the groupconsisting of antibiotics, enzyme inhibitors, antihistamines,anti-inflammatory agents, muscle relaxants, anti-spasmodics, analgesics,prostaglandins, anti-depressants, trophic factors, and hormones.

In yet other embodiments of the first aspect of the invention, thepharmaceutically acceptable fluid is selected from water, saline, aphosphate buffer, a biological fluid, in particular, blood or a fluidthat includes blood components, and glycerol. The method also includesinjecting the flowable bone cement into two or more vertebral bodies. Inaddition, the vertebral body may be fractured or osteoporotic bone. Inother embodiments, the calcium phosphate material has crystals withinthe range of 30-80 nm (e.g., 30-50 nm) or has a crystallinity indexvalue of less than 60% (preferably less than 50%, and more preferablyless than 40%) relative to hydroxyapatite.

In other embodiments, the method involves a minimally invasive surgery,which entails the formation of one or more tiny (less than 2 inches,more preferably less than 1 inch) incisions that allow insertion of asyringe needle through the incision to the site of the vertebral body.The flowable bone cement can be administered through a syringe, whicheliminates the need for a large entry point into the patient. The methodreduces surgical complications (e.g., muscle stripping, blood lossetc.), reduces operative trauma (e.g., by preserving soft tissue) andpostoperative pain, reduces patient hospitalization time, increases thespeed of functional recovery and decreases recovery time (e.g., to a fewmonths rather than a year or more), and leaves a few tiny scars insteadof one large scar.

A second aspect of the invention features a flowable bone cement thatincludes a calcium phosphate material (e.g., a nanocrystalline apatite(NCA) or a nano-low crystalline apatite (NLCA), which can be synthesizedusing, e.g., a low temperature double decomposition technique or a highenergy grinding technique) and a pharmaceutically acceptable fluid(e.g., water, saline, a phosphate buffer, a biological fluid, inparticular, blood or a fluid that includes blood components, andglycerol), wherein said flowable bone cement is injectable (e.g.,through a needle having a size of at least 16 gauge or less (e.g., 11gauge or less)) and hardens in less than 1 hour at 37° C. and, afterhardening, has a compressive strength of 1 mPa or greater and isresorbable in vivo. In an embodiment, the flowable bone cement includesa radio-opaque agent or a supplemental agent (e.g., a cohesivenessagent, an osteogenic agent, and a medicinal agent). In otherembodiments, the calcium phosphate material is chemically bonded using apolymer (e.g., polylactic acid) or other chemical bonding agent (e.g.,HEMA). In other embodiments, the calcium phosphate is selected fromamorphous calcium phosphate, poorly crystalline calcium phosphate,hydroxyapatite, carbonated apatite (calcium-deficient hydroxyapatite),monocalcium phosphate, calcium metaphosphate, heptacalcium phosphate,dicalcium phosphate dihydrate, tetracalcium phosphate, octacalciumphosphate, calcium pyrophosphate, and tricalcium phosphate, or mixturesthereof. In yet other embodiments, the flowable bone cement includes apore-forming agent, e.g., an effervescent agent, at least one agent thatpromotes bone growth or inhibits bone resorption, demineralized bonematrix, or one or more crystal growth inhibitors, or is formed by usingbenzoyl peroxide powder or hydroxyethyl methacrylate (HEMA) anddimethyl-ρ-toluidine.

In yet other embodiments of the second aspect of the invention, thecalcium phosphate has crystals within the range of 30-80 nm (e.g., 30-50nm) or has a crystallinity index value of less than 60% (preferably lessthan 50% and more preferably less than 40%) relative to hydroxyapatite.

A third aspect of the invention features a kit that includes theflowable bone cement of the second aspect of the invention and a syringefor delivery of the flowable bone cement.

A fourth aspect of the invention features a method for makingnanocrystalline apatite (NCA) and nano-low crystalline apatite (NLCA)CaP materials using a low temperature double decomposition technique ora high energy grinding technique and adding a cohesiveness agent or bychemically bonding the CaP material using a polymer (e.g., polylacticacid) or, e.g., HEMA, to form a flowable bone cement that is capable ofhardening at 37° C. in less than 2 hours, preferably less than 1 hour,more preferably less than 30 minutes, and most preferably between 10 and30 minutes and that, prior to hardening, can be injected using a 16gauge or less needle (e.g., an 11 gauge needle). Once hardened, thematerial has a compressive strength of 1 mPa or greater (e.g., acompressive strength in the range of about 1 MPa to about 150 MPa (e.g.,2, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or 120 MPa or greater)).

As used herein, the term “about” means±10% of the recited value.

As used herein, a “biocompatible” substance is one that does not producean unacceptable or undesirable physiological response, e.g., an immuneresponse, in the recipient.

As used herein and applied to a CaP composite of the invention, the term“cohesiveness” means the ability of CaP composite to maintain its shapewithout loss of mass. A composite is deemed cohesive if greater than 90%of its initial mass and volume are retained within its initial shapedimension following incubation in an aqueous environment for at least 10minutes.

By “bioresorabable” is meant capable of being degraded or metabolized invivo by the body and resorbed and/or eliminated through normal excretoryroutes by the body. Such metabolites or break-down products should besubstantially non-toxic to the body.

As used herein, a “cohesiveness agent” means an additive that, whenincluded in a CaP composite of the invention, improves the ability ofthe CaP composite to maintain its cohesiveness. Preferred cohesivenessagents include polymers selected from polysaccharides, nucleic acids,carbohydrates, proteins, polypeptides, poly(α-hydroxy acids),poly(lactones), poly(amino acids), poly(anhydrides), poly(orthoesters),poly(anhydride-co-imides), poly(orthocarbonates), poly(α-hydroxyalkanoates), poly(dioxanones), poly(phosphoesters), poly(L-lactide)(PLLA), poly(D,L-lactide) (PDLLA), polyglycolide (PGA),poly(lactide-co-glycolide (PLGA), poly(L-lactide-co-D, L-lactide),poly(D,L-lactide-co-trimethylene carbonate), polyhydroxybutyrate (PHB),poly(ε-caprolactone), poly(δ-valerolactone), poly(γ-butyrolactone),poly(caprolactone), polyacrylic acid, polycarboxylic acid,poly(allylamine hydrochloride), poly(diallyldimethylammonium chloride),poly(ethyleneimine), polypropylene fumarate, polyvinyl alcohol,polyvinylpyrrolidone, polyethylene, polymethylmethacrylate, carbonfibers, poly(ethylene glycol), poly(ethylene oxide), poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof. Preferred cohesivenessagents also include alginic acid, arabic gum, guar gum, xantham gum,gelatin, chitin, chitosan, chitosan acetate, chitosan lactate,chondroitin sulfate, N,O-carboxymethyl chitosan, a dextran (e.g.,α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, or sodium dextransulfate), fibrin glue, glycerol, hyaluronic acid, sodium hyaluronate, acellulose (e.g., methylcellulose, carboxy methylcellulose, hydroxypropylmethylcellulose, or hydroxyethyl cellulose), a glucosamine, aproteoglycan, a starch (e.g., hydroxyethyl starch or starch soluble),lactic acid, a pluronic, sodium glycerophosphate, collagen, glycogen, akeratin, silk, and mixtures thereof.

BRIEF DESCRIPTION OF THE FIGURES

The invention is described with reference to the following figures,which are presented for the purpose of illustration only and which arenot intended to be limiting of the invention.

FIG. 1 is an X-ray image showing injection of the calcium phosphatematerial of the present invention (containing a radio-opaque agent;bottom needle) into a vertebral body of a human.

FIG. 2 is an X-ray image showing dispersal of the calcium phosphatematerial into the vertebral body (bottom needle) following injection.

FIG. 3 is a photograph showing an external view during injection of thecalcium phosphate material into the vertebra of a human.

DETAILED DESCRIPTION OF THE INVENTION

The present invention features a biocompatible, injectable,self-setting, cohesive, bone-bonding, and remodeling calcium phosphatecomposite (CaP-Comp) material that can be used for vertebroplastyaugmentation and kyphoplasty.

The present invention features several CaP formulations prepared bycreating a chemical bond between an adhesive agent (e.g., a polymer) anda CaP material. The CaP component is not just physically mixed with theadhesive agent but is chemical bonded, e.g., by using a low temperaturedouble decomposition wet chemistry process (see, e.g., U.S. Pat. No.5,783,217, incorporated herein by reference), a high energy grindingprocess (see, e.g., U.S. Pat. Nos. 7,318,841 and 6,840,961, both ofwhich are incorporated herein by reference), or both. In an embodiment,the CaP material is formulated as a nano-crystalline apatite (NCA) or anano-low crystalline apatite (NLCA). These apatites are synthesized,e.g., by using the low temperature double decomposition techniquediscussed above.

The CaP composites of the present invention can also be prepared usingone or more polymers, including, e.g., polylactic Acid (PLA), which arepolymerized with the CaP by physical fixation.

The CaP composites of the present invention can also be prepared usingone or more polymers, including, e.g., hydroxyethyl methacrylate (HEMA)monomers, which are used to polymerize the CaP using a chemical linkage(CaP Co-Polymerization (covalent binding)). The chemical bond may beformed through phosphate ions, which may partially replace the hydroxylions of apatite.

Unlike PMMA cement, the CaP composites of the present invention can beremodeled into bone. Moreover, the CaP composites of the invention donot contain volatile monomers that can be “leached” away from thecomposite after it has been applied to the grafting site (e.g., invertebroplasty or kyphoplasty applications), and thus, the present CaPcomposites can substantially reduce the potential for significant sideeffects observed in PMMA applications.

Moreover, the CaP composites of the present invention can be formulatedfor injection (injectable), can be formulated as a formable material,which can be molded into a desired shape (e.g., formable) beforeimplantation or at the implant site, and is biodegradable. Furthermore,the CaP composites of the invention can be used in therapeuticapplications (e.g., the treatment of vertebral compression fractures) orfor prophylactic applications (e.g., the augmentation of bone, such asosteoporotic bone (e.g., vertebrae)). For example, the percutaneousinjection of a CaP composite of the invention into an osteoporoticvertebral body can substantially increase its fracture strength andstiffness. Moreover, injection of a CaP composite of the invention intoa vertebral compression fracture can partially restore vertebral heightand substantially prevent further vertebral collapse while avoidingpotential problems associated with the use of PMMA.

The CaP composites of the present invention can also be used to augmentthe implantation of pedicle screws into osteoporotic human vertebrate.The CaP composites of the invention provide improved stability ofpedicle screws in osteoporotic human vertebrae both for pullout andcyclic loading relative to other fixation compositions.

In an embodiment, the CaP composites of the invention include abiocompatible cohesiveness agent. In preferred embodiments, thecohesiveness agent includes one or more polymers selected frompolysaccharides, nucleic acids, carbohydrates, proteins, polypeptides,poly(α-hydroxy acids), poly(lactones), poly(amino acids),poly(anhydrides), poly(orthoesters), poly(anhydride-co-imides),poly(orthocarbonates), poly(α-hydroxy alkanoates), poly(dioxanones),poly(phosphoesters), poly(L-lactide) (PLLA), poly(D,L-lactide) (PDLLA),polyglycolide (PGA), poly(lactide-co-glycolide (PLGA),poly(L-lactide-co-D, L-lactide), poly(D,L-lactide-co-trimethylenecarbonate), polyhydroxybutyrate (PHB), poly(ε-caprolactone),poly(δ-valerolactone), poly(γ-butyrolactone), poly(caprolactone),polyacrylic acid, polycarboxylic acid, poly(allylamine hydrochloride),poly(diallyldimethylammonium chloride), poly(ethyleneimine),polypropylene fumarate, polyvinyl alcohol, polyvinylpyrrolidone,polyethylene, polymethylmethacrylate, carbon fibers, poly(ethyleneglycol), poly(ethylene oxide), poly(vinyl alcohol),poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof. The cohesiveness agentcan also be a poly(amino acid), in particular polyproline,poly(L-arginine), poly(L-lysine), polysarcosine, poly(L-hydroxyproline),poly(glutamic acid), poly(S-carboxymethyl-L-cysteine), and poly(asparticacid); a homo- or co-polymer that includes one or more monomers selectedfrom the group consisting of acrolein potassium, (meth)acrylamides,(meth)acrylic acid and salts thereof, (meth)acrylates (e.g., hydroxylmethacylate (HEMA), acrylonitrile, ethylene, ethylene glycol,ethyleneimine, ethyleneoxide, styrene sulfonate, vinyl acetate, vinylalcohol, vinyl chloride, and vinylpyrrolidone); or a polyphenoliccomplexing agent (e.g., an agent selected from gallotannins,ellagitannins, taragallotannins, caffetannins, proanthocyanidins,catechin, epicatechin, chlorogenic acid, and arbutin).

Preferred cohesiveness agents also include alginic acid, arabic gum,guar gum, xantham gum, gelatin, chitin, chitosan, chitosan acetate,chitosan lactate, chondroitin sulfate, N,O-carboxymethyl chitosan, adextran (e.g., α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, or sodiumdextran sulfate), fibrin glue, glycerol, hyaluronic acid, sodiumhyaluronate, a cellulose (e.g., methylcellulose, carboxymethylcellulose, hydroxypropyl methylcellulose, or hydroxyethylcellulose), a glucosamine, a proteoglycan, a starch (e.g., hydroxyethylstarch or starch soluble), lactic acid, a pluronic, sodiumglycerophosphate, collagen, glycogen, a keratin, silk, and mixturesthereof. In yet another preferred embodiment, the biocompatiblecohesiveness agent is present in a composition of the invention in anamount in the range of about 0.5 wt % to about 20 wt % (e.g., less thanabout 20 wt %, preferably less than about 10 wt %, more preferably lessthan about 5 wt %, and most preferably less than about 1 wt %).

In addition, the CaP composites may also include aphysiologically-acceptable fluid which, when added to the dry componentsof the composition, produces a self-hardening paste or putty (e.g., thepaste or putty hardens in about 10 minutes to about 2 hours, preferablyin about 10 minutes to about 1 hour, and more preferably in about 10minutes to about 30 minutes). In several embodiments of the invention,suitable physiologically-acceptable fluids include but are not limitedto water, saline, glycerol, and phosphate buffers. In other embodiments,the fluid can be a biological fluid, e.g., any treated or untreatedfluid (including a suspension) associated with living organisms,particularly blood, including whole blood, warm or cold blood, andstored or fresh blood; treated blood, such as blood diluted with atleast one physiological solution, including but not limited to saline,nutrient, and/or anticoagulant solutions; blood components, such asplatelet concentrate (PC), apheresed platelets, platelet-rich plasma(PRP), platelet-poor plasma (PPP), platelet-free plasma, plasma, serum,fresh frozen plasma (FFP), components obtained from plasma, packed redcells (PRC), buffy coat (BC); blood products derived from blood or ablood component or derived from bone marrow; red cells separated fromplasma and resuspended in physiological fluid; and platelets separatedfrom plasma and resuspended in physiological fluid.

The CaP composites of the invention, once hydrated to form an paste orputty, demonstrate flow characteristics that allow them to be easilyinjected. Varying amounts of fluid may be added to the dry ingredientsof the CaP composites to produce a paste having the desiredcharacteristics. For example, in at least some embodiments, 0.5-2.0 ccof fluid per gram of powder is used to prepare a paste that is formable,i.e., capable of being molded and retaining its shape. In at least someembodiments, the paste is injectable, i.e., capable of passing through a16- to 18-gauge needle. The paste can also be prepared for deliverythrough a catheter (e.g., a catheter having a 7-15 gauge needle, andmore preferably a 7, 8, 9, 10, 11, 12, 13, 14, or 15 gauge needle). Onceinjected, the CaP composite retains its shape and position.

In another aspect, the CaP composite, when hydrated, produces aformable, self-hardening paste, which is moldable and cohesive whenapplied to an implant site in vivo, or an injectable, self-hardeningcomposition that can be injected at the site of bone repair (e.g., avertebral body); both the formable and the injectable compositions arecapable of hardening at the implant site. Again, the compositions retaintheir shape and position once injected. In at least some embodiments,the paste hardens to form a CaP composite (e.g., a NCA or a NCLA) havingsignificant compressive strength. The CaP composite may be implanted orinjected in vivo in paste form or as a hardened CaP composite (e.g.,molded into a desired shape, such as the shape of a bone defect to bereplaced). The CaP composites of the invention can be used to repairbone, e.g., damaged bone, such as damaged vertebral bone.

According to some embodiments, the CaP composite additionally includes abiologically active agent. Biologically active agents that can be usedin the compositions and methods described herein include, withoutlimitation, an antibody, an antibiotic, a polynucleotide, a polypeptide,a protein (e.g., an osteogenic protein), an anti-cancer agent, a growthfactor, and a vaccine. Osteogenic proteins include, without limitation,BMP-2, BMP-3, BMP-3b, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9, BMP-10,BMP-11, BMP-12, BMP-13, BMP-14, BMP-15, BMP-16, BMP-17, and BMP-18.Anti-cancer agents include, without limitation, alkylating agents,platinum agents, antimetabolites, topoisomerase inhibitors, antitumorantibiotics, antimitotic agents, aromatase inhibitors, thymidylatesynthase inhibitors, DNA antagonists, farnesyltransferase inhibitors,pump inhibitors, histone acetyltransferase inhibitors, metalloproteinaseinhibitors, ribonucleoside reductase inhibitors, TNF alpha agonists, TNFalpha antagonists, endothelin A receptor antagonists, retinoic acidreceptor agonists, immuno-modulators, hormonal agents, antihormonalagents, photodynamic agents, and tyrosine kinase inhibitors.

In another preferred embodiment, the CaP composite includesdemineralized bone matrix (DBM). In a preferred embodiment, the DBM hasa particle size in the range of 53-850 μm. In other embodiments, the DBMhas a particle size in the range of 53-125 μm (i.e., fines) or 125-850μm (i.e., full range DBM particles). In yet other embodiments, the DBMis provided as fibers having a fiber length in the range of about 250 μmto about 2 mm.

In other embodiments, the CaP composite includes a contrast agent (e.g.,a barium apatite contrast agent; see, e.g., U.S. Patent ApplicationPublication No. 2005/0257714, incorporated herein by reference).

In other embodiments, the CaP composites include calcium phosphatecomponents that have a Ca/P ratio of less than 1.67. In particularlypreferred embodiments, the CaP composites harden to form a compositionhaving an overall Ca/P ratio in the range of 1.0-1.67, preferably1.3-1.65, more preferably 1.4-1.6, and most preferably close to that ofnaturally occurring bone, that is in the range of 1.45 to 1.67. In apreferred embodiment, the CaP composites have a Ca/P ratio of equal toor less than about 1.5.

In yet other embodiments, the CaP composites of the invention exhibit acompressive strength of equal to or greater than about 1 or 2 MPa. Inother preferred embodiments, the compressive strength is in the range ofabout 1 MPa to about 150 MPa (e.g., 20, 30, 40, 50, 60, 70, 80, 90, or100 MPa). In yet other preferred embodiments, the compressive strengthis 120 MPa or greater (e.g., 120 to 150 MPa).

In other embodiments, the CaP component of the CaP composites has anaverage crystalline domain size of less than 100 nm (e.g., in the rangeof between about 1 nm to about 99 nm; preferably 50 nm or less; morepreferably 40, 30, 20, 10 nm or less).

The tensile strength of the crystal improves the composite's strength,and the smaller the crystal (of CaP) the better. Below a critical sizeparticle (around 30 nanometers), a cracked crystal has the same fracturestrength as a defect-free crystal.

In yet other embodiments, the CaP composite includes a radio-opaqueagent. Non-limiting examples of radio-opaque agents include barium(e.g., barium carbonate and barium sulfate), iodine (e.g., methylmethacrylate, 2-(2′-iodobenzoyl)-ethyl methacrylate), lanthanum oxide,and zirconium dioxide. In other embodiments, the radio-opaque agent ispresent in the CaP composite in an amount of 20% or less by weight,preferably 5% or less by weight, and more preferably 1% or less byweight.

Biocompatible Cohesiveness Agents for Use in the CaP Composites of theInvention

The CaP composites of the present invention may include a biocompatiblecohesiveness agent. Non-limiting examples of suitable biocompatiblecohesiveness agents include polymers selected from polysaccharides,nucleic acids, carbohydrates, proteins, polypeptides, poly(α-hydroxyacids), poly(lactones), poly(amino acids), poly(anhydrides),poly(orthoesters), poly(anhydride-co-imides), poly(orthocarbonates),poly(α-hydroxy alkanoates), poly(dioxanones), poly(phosphoesters),poly(L-lactide) (PLLA), poly(D,L-lactide) (PDLLA), polyglycolide (PGA),poly(lactide-co-glycolide (PLGA), poly(L-lactide-co-D, L-lactide),poly(D,L-lactide-co-trimethylene carbonate), polyhydroxybutyrate (PHB),poly(ε-caprolactone), poly(δ-valerolactone), poly(γ-butyrolactone),poly(caprolactone), polyacrylic acid, polycarboxylic acid,poly(allylamine hydrochloride), poly(diallyldimethylammonium chloride),poly(ethyleneimine), polypropylene fumarate, polyvinyl alcohol,polyvinylpyrrolidone, polyethylene, polymethylmethacrylate, carbonfibers, poly(ethylene glycol), poly(ethylene oxide), poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof. Preferred cohesivenessagents also include alginic acid, arabic gum, guar gum, xantham gum,gelatin, chitin, chitosan, chitosan acetate, chitosan lactate,chondroitin sulfate, N,O-carboxymethyl chitosan, a dextran (e.g.,α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, or sodium dextransulfate), fibrin glue, glycerol, hyaluronic acid, sodium hyaluronate, acellulose (e.g., methylcellulose, carboxy methylcellulose, hydroxypropylmethylcellulose, or hydroxyethyl cellulose), a glucosamine, aproteoglycan, a starch (e.g., hydroxyethyl starch or starch soluble),lactic acid, a pluronic, sodium glycerophosphate, collagen, glycogen, akeratin, silk, and mixtures thereof. In some embodiments, thebiocompatible cohesiveness agent is water-soluble. A water-solublecohesiveness agent dissolves from the implant material shortly after itsimplantation in vivo, thereby introducing macroporosity into the boneimplant material. This macroporosity increases the osteoconductivity ofthe bone implant material by enhancing the access and, consequently, theremodeling activity of the osteoclasts and osteoblasts at the implantsite.

The biocompatible cohesiveness agent may be added to the CaP compositesof the invention in varying amounts and at a variety of stages duringthe production of the powder component. The biocompatible cohesivenessagent is present in a range of about 1 to 50 weight percent. In severalembodiments of the invention, the biocompatible cohesiveness agent ispresent in an amount less than or equal to 40 weight percent of thepowder component, preferably less than or equal to 30 weight percent,more preferably less than or equal to 20 weight percent, and mostpreferably less than or equal to 10 weight percent. In a preferredembodiment, the biocompatible cohesiveness agent is present in an amountof about 5 weight percent.

In an embodiment of the invention, the CaP composite includes DBM. Insome instances, the DBM content of the bone implant material is so highthat, notwithstanding the formability and cohesiveness provided by thecalcium phosphate component of the composite, a cohesiveness agent maybe desirable to further augment the mechanical strength of the boneimplant material during implantation. In particular embodiments, thebiocompatible cohesiveness agent is present in an amount of about 10weight percent of the powder component. In a preferred embodiment, thecalcium phosphate composition includes DBM in an amount of about 40 to50 weight percent, a calcium phosphate component in an amount of about35 to 45 weight percent, a cohesiveness agent in an amount of about 5 to10 weight percent, and an effervescent agent in an amount of about 5 to10 weight percent, such that the combination of all of the componentstotals 100 weight percent. The biocompatible cohesiveness agent may beadded to the DBM particles as a solution; for example, the cohesivenessagent can coat the DBM particles. The biocompatible cohesiveness agentmay be added to the powder component of the composition, including theDBM particles and the calcium phosphate powder. Those of skill in theart will be able to determine the amount of cohesiveness agent andmethod of inclusion required for a given application.

Biologically Active Agents

The CaP composite of the invention can also include a biologicallyactive agent. In general, the biologically active agent should remainactive within the paste during manufacture of the CaP composite, or becapable of being subsequently activated or re-activated followingmanufacture of the CaP composite. Alternatively, the biologically activeagent can be added at the time of implantation of the CaP composite(whether as a moldable or injectable paste or as a hardened cement) intoa host or following hardening at 37° C. in an aqueous environment.

Biologically active agents that can be incorporated into the CaPcomposites of the invention include, without limitation, organicmolecules, inorganic materials, proteins, peptides, nucleic acids (e.g.,genes, gene fragments, gene regulatory sequences, and antisensemolecules), nucleoproteins, polysaccharides, glycoproteins, andlipoproteins. Classes of biologically active compounds that can beincorporated into the compositions of the invention include, withoutlimitation, anti-cancer agents, antibiotics, analgesics,anti-inflammatory agents, immunosuppressants, enzyme inhibitors,antihistamines, anti-convulsants, hormones, muscle relaxants,anti-spasmodics, ophthalmic agents, prostaglandins, anti-depressants,anti-psychotic substances, trophic factors, osteoinductive proteins,growth factors, and vaccines.

Anti-cancer agents include alkylating agents, platinum agents (e.g.,cisplatin), antimetabolites, topoisomerase inhibitors, antitumorantibiotics, antimitotic agents, aromatase inhibitors, thymidylatesynthase inhibitors, DNA antagonists, farnesyltransferase inhibitors,pump inhibitors, histone acetyltransferase inhibitors, metalloproteinaseinhibitors, ribonucleoside reductase inhibitors, TNF alphaagonists/antagonists, endothelin A receptor antagonists, retinoic acidreceptor agonists, immuno-modulators, hormonal and antihormonal agents,photodynamic agents, and tyrosine kinase inhibitors.

Any of the biologically active agents listed in Table 1 can be used.

TABLE 1 Alkylating agents cyclophosphamide lomustine busulfanprocarbazine ifosfamide altretamine melphalan estramustine phosphatehexamethylmelamine mechlorethamine thiotepa streptozocin chlorambuciltemozolomide dacarbazine semustine carmustine Platinum agents cisplatincarboplatinum oxaliplatin ZD-0473 (AnorMED) spiroplatinum, lobaplatin(Aeterna) carboxyphthalatoplatinum, satraplatin (Johnson Matthey)tetraplatin BBR-3464 (Hoffmann-La Roche) ormiplatin SM-11355 (Sumitomo)iproplatin AP-5280 (Access) Antimetabolites azacytidine tomudexgemcitabine trimetrexate capecitabine deoxycoformycin 5-fluorouracilfludarabine floxuridine pentostatin 2-chlorodeoxyadenosine raltitrexed6-mercaptopurine hydroxyurea 6-thioguanine decitabine (SuperGen)cytarabin clofarabine (Bioenvision) 2-fluorodeoxy cytidine irofulven(MGI Pharma) methotrexate DMDC (Hoffmann-La Roche) idatrexateethynylcytidine (Taiho) Topoisomerase amsacrine rubitecan (SuperGen)inhibitors epirubicin exatecan mesylate (Daiichi) etoposide quinamed(ChemGenex) teniposide or mitoxantrone gimatecan (Sigma-Tau) irinotecan(CPT-11) diflomotecan (Beaufour-Ipsen) 7-ethyl-10-hydroxy-camptothecinTAS-103 (Taiho) topotecan elsamitrucin (Spectrum) dexrazoxanet(TopoTarget) J-107088 (Merck & Co) pixantrone (Novuspharma) BNP-1350(BioNumerik) rebeccamycin analogue (Exelixis) CKD-602 (Chong Kun Dang)BBR-3576 (Novuspharma) KW-2170 (Kyowa Hakko) Antitumor dactinomycin(actinomycin D) amonafide antibiotics doxorubicin (adriamycin) azonafidedeoxyrubicin anthrapyrazole valrubicin oxantrazole daunorubicin(daunomycin) losoxantrone epirubicin bleomycin sulfate (blenoxane)therarubicin bleomycinic acid idarubicin bleomycin A rubidazonebleomycin B plicamycinp mitomycin C porfiromycin MEN-10755 (Menarini)cyanomorpholinodoxorubicin GPX-100 (Gem Pharmaceuticals) mitoxantrone(novantrone) Antimitotic paclitaxel SB 408075 (GlaxoSmithKline) agentsdocetaxel E7010 (Abbott) colchicine PG-TXL (Cell Therapeutics)vinblastine IDN 5109 (Bayer) vincristine A 105972 (Abbott) vinorelbine A204197 (Abbott) vindesine LU 223651 (BASF) dolastatin 10 (NCI) D 24851(ASTAMedica) rhizoxin (Fujisawa) ER-86526 (Eisai) mivobulin(Warner-Lambert) combretastatin A4 (BMS) cemadotin (BASF)isohomohalichondrin-B (PharmaMar) RPR 109881A (Aventis) ZD 6126(AstraZeneca) TXD 258 (Aventis) PEG-paclitaxel (Enzon) epothilone B(Novartis) AZ10992 (Asahi) T 900607 (Tularik) IDN-5109 (Indena) T 138067(Tularik) AVLB (Prescient NeuroPharma) cryptophycin 52 (Eli Lilly)azaepothilone B (BMS) vinflunine (Fabre) BNP-7787 (BioNumerik)auristatin PE (Teikoku Hormone) CA-4 prodrug (OXiGENE) BMS 247550 (BMS)dolastatin-10 (NIH) BMS 184476 (BMS) CA-4 (OXiGENE) BMS 188797 (BMS)taxoprexin (Protarga) Aromatase aminoglutethimide exemestane inhibitorsletrozole atamestane (BioMedicines) anastrazole YM-511 (Yamanouchi)formestane Thymidylate pemetrexed (Eli Lilly) nolatrexed (Eximias)synthase inhibitors ZD-9331 (BTG) CoFactor ™ (BioKeys) DNA antagoniststrabectedin (PharmaMar) mafosfamide (Baxter International) glufosfamide(Baxter International) apaziquone (Spectrum albumin + 32P (IsotopeSolutions) Pharmaceuticals) thymectacin (NewBiotics) O6 benzyl guanine(Paligent) edotreotide (Novartis) Farnesyltransferase arglabin(NuOncology Labs) tipifarnib (Johnson & Johnson) inhibitors lonafarnib(Schering-Plough) perillyl alcohol (DOR BioPharma) BAY-43-9006 (Bayer)Pump inhibitors CBT-1 (CBA Pharma) zosuquidar trihydrochloride (Elitariquidar (Xenova) Lilly) MS-209 (Schering AG) biricodar dicitrate(Vertex) Histone tacedinaline (Pfizer) pivaloyloxymethyl butyrate(Titan) acetyltransferase SAHA (Aton Pharma) depsipeptide (Fujisawa)inhibitors MS-275 (Schering AG) Metalloproteinase Neovastat (AeternaLaboratories) CMT-3 (CollaGenex) inhibitors marimastat (British Biotech)BMS-275291 (Celltech) Ribonucleoside gallium maltolate (Titan)tezacitabine (Aventis) reductase inhibitors triapine (Vion) didox(Molecules for Health) TNF alpha virulizin (Lorus Therapeutics) revimid(Celgene) agonists/antagonists CDC-394 (Celgene) Endothelin A atrasentan(Abbott) YM-598 (Yamanouchi) receptor antagonist ZD-4054 (AstraZeneca)Retinoic acid fenretinide (Johnson & Johnson) alitretinoin (Ligand)receptor agonists LGD-1550 (Ligand) Immuno- interferon dexosome therapy(Anosys) modulators oncophage (Antigenics) pentrix (Australian CancerGMK (Progenics) Technology) adenocarcinoma vaccine (Biomira) ISF-154(Tragen) CTP-37 (AVI BioPharma) cancer vaccine (Intercell) IRX-2(Immuno-Rx) norelin (Biostar) PEP-005 (Peplin Biotech) BLP-25 (Biomira)synchrovax vaccines (CTL Immuno) MGV (Progenics) melanoma vaccine (CTLImmuno) β-alethine (Dovetail) p21 RAS vaccine (GemVax) CLL therapy(Vasogen) Hormonal and estrogens prednisone antihormonal conjugatedestrogens methylprednisolone agents ethinyl estradiol prednisolonechlortrianisen aminoglutethimide idenestrol leuprolidehydroxyprogesterone caproate goserelin medroxyprogesterone leuporelintestosterone bicalutamide testosterone propionate; flutamidefluoxymesterone octreotide methyltestosterone nilutamidediethylstilbestrol mitotane megestrol P-04 (Novogen) tamoxifen2-methoxyestradiol (EntreMed) toremofine arzoxifene (Eli Lilly)dexamethasone Photodynamic talaporfin (Light Sciences)Pd-bacteriopheophorbide (Yeda) agents Theralux (Theratechnologies)lutetium texaphyrin (Pharmacyclics) motexafin gadolinium (Pharmacyclics)hypericin Tyrosine Kinase imatinib (Novartis) kahalide F (PharmaMar)Inhibitors leflunomide (Sugen/Pharmacia) CEP-701 (Cephalon) ZD1839(AstraZeneca) CEP-751 (Cephalon) erlotinib (Oncogene Science) MLN518(Millenium) canertinib (Pfizer) PKC412 (Novartis) squalamine (Genaera)phenoxodiol () SU5416 (Pharmacia) trastuzumab (Genentech) SU6668(Pharmacia) C225 (ImClone) ZD4190 (AstraZeneca) rhu-Mab (Genentech)ZD6474 (AstraZeneca) MDX-H210 (Medarex) vatalanib (Novartis) 2C4(Genentech) PKI166 (Novartis) MDX-447 (Medarex) GW2016 (GlaxoSmithKline)ABX-EGF (Abgenix) EKB-509 (Wyeth) IMC-1C11 (ImClone) EKB-569 (Wyeth)

The CaP composites can also include medicinal agents, e.g., antibiotics,such as aminoglycosides (e.g., gentamicin, tobramycin, netilmicin,streptomycin, amikacin, neomycin), bacitracin, corbapenems (e.g.,imipenem/cislastatin), cephalosporins, colistin, methenamine,monobactams (e.g., aztreonam), penicillins (e.g., penicillin G,penicillin V, methicillin, natcillin, oxacillin, cloxacillin,dicloxacillin, ampicillin, amoxicillin, carbenicillin, ticarcillin,piperacillin, mezlocillin, azlocillin), polymyxin B, quinolones, andvancomycin; and bacteriostatic agents such as chloramphenicol,clindanyan, macrolides (e.g., erythromycin, azithromycin,clarithromycin), lincomyan, nitrofurantoin, sulfonamides, tetracyclines(e.g., tetracycline, doxycycline, minocycline, demeclocyline), andtrimethoprim. Also included are metronidazole, fluoroquinolones, andritampin.

Enzyme inhibitors are substances that inhibit an enzymatic reaction.Examples of enzyme inhibitors that can be included in the CaP compositesof the invention include, e.g., edrophonium chloride,N-methylphysostigmine, neostigmine bromide, physostigmine sulfate,tacrine, tacrine, 1-hydroxy maleate, iodotubercidin, p-bromotetramisole,10-(alpha-diethylaminopropionyl)-phenothiazine hydrochloride,calmidazolium chloride, hemicholinium-3, 3,5-dinitrocatechol,diacylglycerol kinase inhibitor I, diacylglycerol kinase inhibitor II,3-phenylpropargylamine, N⁶-monomethyl-L-arginine acetate, carbidopa,3-hydroxybenzylhydrazine, hydralazine, clorgyline, deprenyl,hydroxylamine, iproniazid phosphate, 6-MeO-tetrahydro-9H-pyrido-indole,nialamide, pargyline, quinacrine, semicarbazide, tranylcypromine,N,N-diethylaminoethyl-2,2-diphenylvalerate hydrochloride,3-isobutyl-1-methylxanthne, papaverine, indomethacind,2-cyclooctyl-2-hydroxyethylamine hydrochloride,2,3-dichloro-a-methylbenzylamine (DCMB),8,9-dichloro-2,3,4,5-tetrahydro-1H-2-benzazepine hydrochloride,p-aminoglutethimide, p-aminoglutethimide tartrate, 3-iodotyrosine,alpha-methyltyrosine, acetazolamide, dichlorphenamide,6-hydroxy-2-benzothiazolesulfonamide, and allopurinol.

Antihistamines that can be included in CaP composites of the inventioninclude, e.g., pyrilamine, chlorpheniramine, and tetrahydrazoline, amongothers.

Anti-inflammatory agents that can be included in CaP composites of theinvention include, e.g., corticosteroids, nonsteroidal anti-inflammatorydrugs (e.g., aspirin, phenylbutazone, indomethacin, sulindac, tolmetin,ibuprofen, piroxicam, and fenamates), acetaminophen, phenacetin, goldsalts, chloroquine, D-Penicillamine, methotrexate colchicine,allopurinol, probenecid, and sulfinpyrazone.

Muscle relaxants that can be included in CaP composites of the inventioninclude, e.g., mephenesin, methocarbomal, cyclobenzaprine hydrochloride,trihexylphenidyl hydrochloride, levodopa/carbidopa, and biperiden.

Anti-spasmodics that can be included in CaP composites of the inventioninclude, e.g., atropine, scopolamine, oxyphenonium, and papaverine.

Analgesics that can be included in CaP composites of the inventioninclude, e.g., aspirin, phenybutazone, idomethacin, sulindac, tolmetic,ibuprofen, piroxicam, fenamates, acetaminophen, phenacetin, morphinesulfate, codeine sulfate, meperidine, nalorphine, opioids (e.g., codeinesulfate, fentanyl citrate, hydrocodone bitartrate, loperamide, morphinesulfate, noscapine, norcodeine, normorphine, thebaine,nor-binaltorphimine, buprenorphine, chlornaltrexamine, funaltrexamione,nalbuphine, nalorphine, naloxone, naloxonazine, naltrexone, andnaltrindole), procaine, lidocain, tetracaine and dibucaine.

Ophthalmic agents that can be included in CaP composites of theinvention include, e.g., sodium fluorescein, rose bengal, methacholine,adrenaline, cocaine, atropine, alpha-chymotrypsin, hyaluronidase,betaxalol, pilocarpine, timolol, timolol salts, and combinationsthereof.

Prostaglandins, which are art recognized as a class of naturallyoccurring chemically related, long-chain hydroxy fatty acids that have avariety of biological effects, can also be included in CaP composites ofthe invention.

Anti-depressants are substances capable of preventing or relievingdepression. Examples of anti-depressants that can be included in CaPcomposites of the invention include, e.g., imipramine, amitriptyline,nortriptyline, protriptyline, desipramine, amoxapine, doxepin,maprotiline, tranylcypromine, phenelzine, and isocarboxazide.

Trophic factors are factors whose continued presence improves theviability or longevity of a cell. Trophic factors that can be includedin CaP composites of the invention include, without limitation,platelet-derived growth factor (PDGP), neutrophil-activating protein,monocyte chemoattractant protein, macrophage-inflammatory protein,platelet factor, platelet basic protein, and melanoma growth stimulatingactivity; epidermal growth factor, transforming growth factor (alpha),fibroblast growth factor, platelet-derived endothelial cell growthfactor, insulin-like growth factor, glial derived growth neurotrophicfactor, ciliary neurotrophic factor, nerve growth factor, bonegrowth/cartilage-inducing factor (alpha and beta), bone morphogeneticproteins, interleukins (e.g., interleukin inhibitors or interleukinreceptors, including interleukin 1 through interleukin 10), interferons(e.g., interferon alpha, beta and gamma), hematopoietic factors,including erythropoietin, granulocyte colony stimulating factor,macrophage colony stimulating factor and granulocyte-macrophage colonystimulating factor; tumor necrosis factors, transforming growth factors(beta), including beta-1, beta-2, beta-3, inhibin, and activin; and bonemorphogenetic proteins such as OP-1, BMP-2 and BMP-7.

Hormones that can be included in CaP composites of the inventioninclude, e.g., estrogens (e.g., estradiol, estrone, estriol,diethylstibestrol, quinestrol, chlorotrianisene, ethinyl estradiol,mestranol), anti-estrogens (e.g., clomiphene, tamoxifen), progestins(e.g., medroxyprogesterone, norethindrone, hydroxyprogesterone,norgestrel), antiprogestin (mifepristone), androgens (e.g, testosteronecypionate, fluoxymesterone, danazol, testolactone), anti-androgens(e.g., cyproterone acetate, flutamide), thyroid hormones (e.g.,triiodothyronne, thyroxine, propylthiouracil, methimazole, andiodixode), and pituitary hormones (e.g., corticotropin, sumutotropin,oxytocin, and vasopressin). Hormones are commonly employed in hormonereplacement therapy and/or for purposes of birth control. Steroidhormones, such as prednisone, which are also used as immunosuppressantsand anti-inflammatories, can be included in CaP composites of theinvention.

Osteogenic Proteins

The biologically active agent is desirably selected from the family ofproteins known as the transforming growth factors-beta (TGF-β)superfamily of proteins, which includes the activins, inhibins, and bonemorphogenetic proteins (BMPs). Most preferably, the active agentincludes at least one protein selected from the subclass of proteinsknown generally as BMPs, which have been disclosed to have osteogenicactivity, and other growth and differentiation type activities. TheseBMPs include BMP proteins BMP-2, BMP-3, BMP-3b, BMP-4, BMP-5, BMP-6 andBMP-7, disclosed for instance in U.S. Pat. Nos. 5,108,922; 5,013,649;5,116,738; 5,106,748; 5,187,076; and 5,141,905; BMP-8, disclosed in PCTpublication WO 91/18098; and BMP-9, disclosed in PCT publication WO93/00432, BMP-10, disclosed in PCT application WO 94/26893; BMP-11,disclosed in PCT application WO 94/26892, or BMP-12 or BMP-13, disclosedin PCT application WO 95/16035; BMP-14; BMP-15, disclosed in U.S. Pat.No. 5,635,372; or BMP-16, disclosed in U.S. Pat. No. 5,965,403. OtherBMPs include BMP-17 and BMP-18.

Other TGF-β proteins that may be useful as the active agent in the CaPcomposites of the invention include, e.g., Vgr-2, Jones et al., Mol.Endocrinol. 6:1961 (1992), and any of the growth and differentiationfactors (GDFs), including those described in PCT applications WO94/15965; WO 94/15949; WO 95/01801; WO 95/01802; WO 94/21681; WO94/15966; WO 95/10539; WO 96/01845; WO 96/02559 and others. Also usefulin the invention may be BIP, disclosed in WO 94/01557; HP00269,disclosed in JP Publication number: 7-250688; and MP52, disclosed in PCTapplication WO 93/16099. The disclosures of all of the aboveapplications are incorporated herein by reference. A subset of BMPswhich are presently preferred for use in the invention include BMP-2,BMP-4, BMP-5, BMP-6, BMP-7, BMP-10, BMP-12, BMP-13, BMP-14, and MP52.The active agent is most preferably BMP-2, the sequence of which isdisclosed in U.S. Pat. No. 5,013,649, the disclosure of which isincorporated herein by reference. Other osteogenic agents known in theart can also be used, such as teriparatide (Forteo™), Chrysalin®,prostaglandin E2, or LIM protein, among others.

The biologically active agent may be recombinantly produced, or purifiedfrom a protein composition. The active agent, if a TGF-β, such as a BMP,or other dimeric protein, may be homodimeric, or may be heterodimericwith other BMPs (e.g., a heterodimer composed of one monomer each ofBMP-2 and BMP-6) or with other members of the TGF-β superfamily, such asactivins, inhibins and TGF-β1 (e.g., a heterodimer composed of onemonomer each of a BMP and a related member of the TGF-β superfamily).Examples of such heterodimeric proteins are described for example inPublished PCT Patent Application WO 93/09229, the specification of whichis hereby incorporated herein by reference.

The biologically active agent may further include additional agents suchas the Hedgehog, Frazzled, Chordin, Noggin, Cerberus and Follistatinproteins. These families of proteins are generally described in Sasai etal., Cell 79:779-790 (1994) (Chordin); PCT Patent Publication WO94/05800 (Noggin); and Fukui et al., Devel. Biol. 159:131 (1993)(Follistatin). Hedgehog proteins are described in WO 96/16668; WO96/17924; and WO 95/18856. The Frazzled family of proteins is a recentlydiscovered family of proteins with high homology to the extracellularbinding domain of the receptor protein family known as Frizzled. TheFrizzled family of genes and proteins is described in Wang et al., J.Biol. Chem. 271:4468-4476 (1996). The active agent may also includeother soluble receptors, such as the truncated soluble receptorsdisclosed in PCT patent publication WO 95/07982. From the teaching of WO95/07982, one skilled in the art will recognize that truncated solublereceptors can be prepared for numerous other receptor proteins. Theabove publications are hereby incorporated by reference herein. Theamount of osteogenic protein effective to stimulate increased osteogenicactivity of present or infiltrating progenitor or other cells willdepend upon the size and nature of the defect being treated, as well asthe carrier being employed.

Generally, the biologically active agent is included in the CaPcomposite in an amount sufficient to treat or ameliorate a bone defector injury (e.g., a vertebral body defect or injury), when the CaPcomposite is being used in connection with bone regeneration. By “anamount sufficient” is meant the amount of a biologically active agentrequired in the CaP composite to promote a clinically relevant effect. Asufficient amount of a biologically active compound used to practice thepresent invention for therapeutic purposes varies depending upon themanner of administration, the age, body weight, and general health ofthe patient. Ultimately, the prescribers will decide the appropriateamount and dosage regimen. The appropriate amounts for any monotherapyor combination therapy described herein can be determined from animalmodels, in vitro assays, and/or clinical studies.

By way of example, the amount of a biologically active agent included inthe CaP composite can be in the range of from about 0.1 ng to about 10.0g per kg; preferably about 1.0 μg to about 1000.0 mg per kg; mostpreferably about 10.0 μg to about 10.0 mg per kg.

Biologically active agents can be introduced into the CaP composites ofthe invention during or after its formation. Agents may conveniently bemixed into the compositions prior to setting. Alternatively, the CaPcomposite may be shaped and hardened and then exposed to the therapeuticagent in solution. This particular approach is particularly well suitedfor proteins, which are known to have an affinity for apatiticmaterials. A buffer solution containing the biologically active agentmay be employed, instead of water, as the aqueous solution in which theself-hardening paste is, for example, irrigated prior to implantation.Buffers may be used in any pH range, but most often will be used in therange of 5.0 to 8.0 in preferred embodiments the pH will be compatiblewith prolonged stability and efficacy of the desired therapeutic agentand, in most preferred embodiments, will be in the range of 5.5 to 7.4.Suitable buffers include, but are not limited to, carbonates, phosphates(e.g., phosphate buffered saline), and organic buffers such as Tris,HEPES, and MOPS. Most often, the buffer will be selected for it'sbiocompatibility with the host tissues and its compatibility with thetherapeutic agent. For most applications of nucleic acids, peptides orantibiotics a simple phosphate buffered saline will suffice.

Demineralized Bone Matrix

In a preferred embodiment, the biologically active agent is DBM. DBM isan organic, osteoinductive material most commonly obtained from longbone chips demineralized by acid treatment. The acid treatment dissolvesinorganic mineral components and acid-soluble proteins in the bone,leaving behind a collagen matrix as well as acid-insoluble proteins andgrowth factors (see, e.g., Glowacki et al. (1985) Clin. Plast. Surg.12(2):233-241; Covey et al. (1989) Orthop. Rev. 17(8):857-863). Amongthe residual acid-insoluble proteins and growth factors areosteoinductive factors, such as bone morphogenic proteins (BMPs) andtransforming growth factors (TGFs). Thus, DBM is osteoinductive, fullyresorbable, and, when used in combination with the calcium phosphatecomponent of the CaP composites described herein, yields bone implantmaterials that are highly biocompatible because they closely mimic thechemical composition of natural bone. Advantageously, DBM costs lessthan many other available organic bone composition additives, such asisolated BMPs.

The DBM employed in the CaP composites of the invention is preferablyderived from autogenic or allogenic sources. As discussed above, DBM maybe obtained by acid treatment of long bone chips, a process well knownto those of ordinary skill in the art. Alternatively, commerciallyavailable DBM may be used (e.g., DBM available from Allosource, AmericanRed Cross, Musculoskeletal Transplant Foundation, RegenerationTechnologies, Inc., and Osteotech, Inc.).

In at least some embodiments, the DBM in the bone implant materials ispresent in an amount between about 10 and about 70 weight percent of thepowder component. In particular embodiments, the DBM is present in anamount equal to about 60 weight percent of the powder component. Inother embodiments, the DBM is present in an amount between about 1 andabout 50 weight percent of the powder component. In still otherembodiments, the DBM is present in an amount less than or equal to about20 weight percent of the powder component. Preferably, the DBM ispresent in an amount less than or equal to about 15 weight percent ofthe powder component.

The amount of DBM in a given composition will vary depending upon theamount of the biocompatible cohesiveness agent, as well as the intendeduse and desired characteristics of the CaP composite. In particularembodiments, the cohesiveness agent and the DBM are present in the CaPcomposite in a ratio of about 1:1 (e.g., in an amount in the range ofabout 0.5 and about 20 weight percent of the powder component),preferably about 1:5, more preferably about 1:10, and most preferablyabout 1:20. In preferred embodiments, the cohesiveness agent is presentin an amount of about 5 weight percent or less.

Those of skill in the art will be able to determine the amount ofbiologically agent agent (e.g., DBM), calcium phosphate, cohesivenessagent, and other agents required for particular applications. Forexample, a preferred calcium phosphate powder composition includes about15 weight percent DBM and about 85 weight percent calcium phosphatepowder having between about 1 to about 10 weight percent cohesivenessagent and effervescent agent. Another preferred calcium phosphate powdercomposition includes about 45 weight percent DBM, about 45 weightpercent calcium phosphate powder and about 10 weight percentbiocompatible cohesiveness agent.

The DBM particles may be of various sizes and physical forms. As withthe amount of DBM, the size and form of the DBM particles will varydepending upon the intended use of the bone implant material. In someembodiments, the DBM particles have a longest dimension measuringbetween about 35 μm and about 850 μm and may further have an aspectratio of less than about 5. In other embodiments, the DBM particles arefibrous in nature. In some embodiments, these DBM fibers have a lengthbetween about 50 μm and about 3 mm. In other embodiments, the DBM fibershave a length between about 250 μm and about 2 mm. In some embodiments,the aspect ratio of these DBM fibers is greater than 4. In otherembodiments, the aspect ratio of these DBM fibers is greater than 10.The DBM fibers may be needle-like, having an average width to averagethickness ratio of less than 5. Methods of producing DBM particles ofvarying sizes will be well-known to those of skill in the art and aredisclosed, for example, in U.S. Patent Application Publication No.2004/0097612, which is incorporated herein by reference. Of note, theneedle-like, fibrous DBM obtained from long bone chips or shavings, asopposed to DBM obtained from ground bone, provide increased cohesivenesswhen incorporated into the calcium phosphate compositions of the presentinvention.

EXAMPLES

The following examples are to illustrate the invention. They are notmeant to limit the invention in any way.

Example 1

Preparation of Nano Crystalline Apatite (NCA) with No Crystal GrowthInhibitor:

Add 100 g of Na₂HPO₄, 7H₂O to 1000 ml of distilled water to prepare asolution of 0.37 M (Solution 1). Add 35 g of Ca(NO₃)₂, 4H₂O to 300 ml ofdistilled water to prepare a solution of 0.49 M (Solution 2).

Add rapidly solution 2 to solution 1, stir vigorously for 5 minutes atroom temperature to produce slurry. After filtration, washing andfreeze-drying (by adding liquid nitrogen into the wet cake), NCAnano-particle is obtained. Activate NCA powder (at 120° C. during 2hours) by removing excessive moisture (about 3 to 10%).

In this example the crystallinity index of NCA produced is estimated (bycomparing with hydroxyapatite) to be around 60% with the nano-sizecrystal range: 30-80 nm.

Example 2

Preparation of Nano Low Crystalline Apatite (NLCA) with One CrystalGrowth Inhibitor (CO₃ ²⁻ Ions):

Add 100 g of Na₂HPO₄, 7H₂O to 1000 ml of distilled water to prepare asolution of 0.37 M. Once dissolved, add 40 g of NaHCO₃ and stir todissolve (Solution 1).

Add 35 g of Ca(NO₃)₂, 4H₂O to 300 ml of distilled water to prepare asolution of 0.49 M (Solution 2).

Add rapidly solution 2 to solution 1, stir vigorously for 5 minutes atroom temperature to produce slurry. After filtration, washing andfreeze-drying (by adding liquid nitrogen into the wet cake), NLCAnano-particle is obtained. Activate NLCA powder (at 120° C. during 2hours) by removing excessive moisture (about 3 to 10%).

In this example the crystallinity index of NLCA produced is estimated(by comparing with hydroxyapatite) to be around 50% with nano-sizecrystal range: 30-50 nm.

Example 3

Preparation of Nano Low Crystalline Apatite (NLCA) with Two CrystalGrowth Inhibitors (CO₃ ²⁻ and P₂O₇ ⁴⁻ Ions):

Add 100 g of Na₂HPO₄, 7H₂O to 1000 ml of distilled water to prepare asolution of 0.37 M. Once dissolved, add 40 g of NaHCO₃ and stir todissolve. Once all dissolved, add 0.5. Na₄P₂O₇, 10H₂O and stir todissolve (Solution 1).

Add 35 g of Ca(NO₃)₂, 4H₂O to 300 ml of distilled water to prepare asolution of 0.49 M (Solution 2).

Add rapidly solution 2 to solution 1, stir vigorously for 5 minutes atroom temperature to produce slurry. After filtration, washing andfreeze-drying (by adding liquid nitrogen into the wet cake), NLCAnano-particle is obtained. Activate NLCA powder (at 120° C. during 2hours) by removing excessive moisture (about 3 to 10%).

In this example the crystallinity index of NLCA produced is estimated(by comparing with hydroxyapatite) to be around 40% with nano-sizecrystal range: 30-50 nm.

Example 4

Preparation of Nano Low Crystalline Apatite (NLCA) with Three CrystalGrowth Inhibitors (CO₃ ²⁻, P₂O₇ ⁴⁻ and Mg²⁺ Ions):

Add 100 g of Na₂HPO₄, 7H₂O to 1000 ml of distilled water to prepare asolution of 0.37 M. Once dissolved, add 40 g of NaHCO₃ and stir todissolve. Once all dissolved, add 0.5. Na₄P₂O₇, 10H₂O and stir todissolve (Solution 1).

Add 35 g of Ca(NO₃)₂, 4H₂O to 300 ml of distilled water to prepare asolution of 0.49 M. Once dissolved, add 0.5 g MgCl₂, 6H₂O (Solution 2).

Add rapidly solution 2 to solution 1, stir vigorously for 5 minutes atroom temperature to produce slurry. After filtration, washing andfreeze-drying (by adding liquid nitrogen into the wet cake), NLCAnano-particle is obtained. Activate NLCA powder (at 120° C. during 2hours) by removing excessive moisture (about 3 to 10%).

In this example the crystallinity index of NLCA produced is estimated(by comparing with hydroxyapatite) to be around 40% with nano-sizecrystal range: 30-50 nm.

Example 5

Co-Polymerization (Physical Fixation of CaP-Polymers):

Prepare apatite (NCA and/or NLCA) powder according to Example 1, 2, 3 or4.

Dissolve about 25 g PLA (Polylactic Acid) powder in a solvent (acetonefor example) in order to obtain a homogenous liquid.

Mix apatite powder with PLA solution (with the ratio of PLA about 25%w/w). Stir vigorously (at room temperature) during 2 h in order toprepare emulsion. Vacuum dry the emulsion during 2 h at 100° C. in orderto remove the residual solvent (by evaporation) and produce a drypowder.

Ground the powder in the high energy dry ball mill process for 1 to 5hours in order to densify the material. The residence time in the highenergy grinding process will first reduce the particle size and thenpartially amorphize the material. By varying the residence time,materials with different mechanical performance can be prepared.

Example 6

Co-Polymerization (Chemical Linkage, Covalent Binding) of CaP Materials:

Prepare apatite (NCA and/or NLCA) powder according to Example 1, 2, 3 or4.

Prepare a homogenous powder by mixing about 20 g apatite powder with 1.2g of Benzoyl Peroxide powder (Powder 1).

Add on 20 g Hydroxyethyl Methacrylate (HEMA), about 0.8 mlDimethyl-ρ-Toluidine and stir to prepare a solution (Solution 1).

Add all of solution 1 to powder 1, at room temperature and stirvigorously to obtain emulsion of Apatite-HEMA. The emulsion is vacuumdried at 80° C., for 4 h to remove all residual solvent by evaporationprocess.

The irreversible link between the ethylenic bond of Apatite-HEMAproduces a hydrophilic material that forms a colloid-like material whenmixed with hydration media (for example, water or any otherpharmaceutically acceptable liquid described herein).

By grinding the powder in the dry ball mill at various conditions(media-powder ratio, residence time, RPM) and compacting/densificationof powder, various self-setting CaP-polymeric cements is produced.

Example 7

Imaging Capability of CaP Paste Injected into Adult Cadaveric Vertebral:

CaP material made according to the recipe developed previously (see,e.g., U.S. Pat. No. 7,318,841, incorporated herein by reference).

CaP cement powder was mixed with 5% (w/w) Sodium Alginate powder.

CaP material was injected into two adult cadaveric vertebral bodies toassess the imaging capabilities (radiopacity) of paste underfluoroscopy.

The hydration media was physiological saline with 20% Renografin-60(organically bond Iodine) solution in order to increase radiopacitycapacity.

Two Adult cadaveric spines were used. Each vertebral body was injected(through 12G long needle) with about 4 cc CaP cement through twopedicles (with in total 6 levels of spine). Each pedicle was injectedseparately.

Injection process conducted successfully with clear visualization ofCaP-Alginate paste through vertebral bodies.

Example 8

CaP Matrix with Cohesiveness Agent (CA):

CaP material made according to the recipe developed previously (see,e.g., U.S. Pat. No. 7,318,841, incorporated herein by reference).

The CA used is sodium alginate with the ratio of 1 to 20 w/w %.

CaP-Alginate (2 w/w %) was previously injected into sheep lumbar (L3-L4)vertebrae (after conducting the defect). At 6 month time point, no signsof acute or chronic inflammation observed. Histology analysis confirmedremodeling and osseointegration on both stained sections andmicroradiographs. Larger quantity of new bone was present and organizedin a concentric lamellar pattern.

Example 9

CaP Matrix with Osteoinductive Agents (OI):

CaP material made according to the recipe developed previously (see,e.g., U.S. Pat. No. 7,318,841, incorporated herein by reference).

The OI used is demineralized bone matrix (DBM) with various ratios,e.g., 1:1 calcium phosphate material (CaP): DBM; 2:1 (CaP:DBM); 3:1(CaP:DBM); 4:1 (CaP:DBM); 5:1 (CaP:DBM); and 10:1 (CaP:DBM).

The CaP/DBM composites are to be injected into sheep lumbar (L3-L4)vertebrae (after conducting the defect). At 6 month time point, theinjection site will be examined for signs of acute or chronicinflammation. Histology analysis, using, e.g., stained sections andmicroradiographs, will be undertaken to confirm that remodeling andosseointegration has occurred.

Example 10

CaP Matrix with Medicinal Agents (MA):

CaP material made according to the recipe developed previously (see,e.g., U.S. Pat. No. 7,318,841, incorporated herein by reference).

The MA used is different kinds of antibiotics with various ratios (e.g.,2:1 (CaP:MA); 10:1 (CaP:MA); 20:1 (CaP:MA); and 50:1 (CaP:MA).

Three common medicinal agents tested (Gentamicin, Tobramycin andVancomycin) did not adversely affect the performance (e.g., hardeningtime and compressive strength) of the CaP composite.

Additional work with Tobramycin showed that at a dosage greater than 100mg/gm hardening was inhibited. At 60 mg/gm or less CaP-Tobramycinhardened normally.

Example 11

Combination Composite:

CaP material made according to the recipe developed previously (see,e.g., U.S. Pat. No. 7,318,841, incorporated herein by reference).

In these engineered formulation various combination materials usingdifferent CaP matrix, CAs, OIs, and MAs are proposed.

Bioresorbable, biocompatible, injectable, self-setting, high-strength,bone-bonding calcium phosphate combination bone graft materials (i.e.,CaP composites) for the treatment of osteoporotic bone is produced.

Example 12

Multiple formulations of CaP composites were tested for applicabilityfor Vertebroplasty in a human cadaver model. CaP composites wereprepared by mixing dry powders of a high strength, fast setting calciumphosphate and carboxyl methyl cellulose (CMC). The dry powders werehydrated and mixed with an iodine based contrast agent, ISOVUE (BraccoDiagnostics), until a smooth paste was formed. Percent CMC, CMCmolecular weight, and hydration volume were varied to create differentCPC formulations.

Each CaP composite formulation was loaded into a delivery syringeattached to an 11 gauge vertebroplasty needle and delivered underfluoroscopy into a separate vertebral body. CaP composites wereevaluated for ease of visualization, ease of delivery, and dispersion. APMMA designed for vertebroplasty use (Cook) was used as a reference.

All CaP composites were easily visualized under fluoroscopy. Higherconcentrations of CMC in the CaP composite, the use of high molecularweight CMC, and a lower hydration volume each contributed to decreaseddispersion and leakage of the CaP composite material from the injectionsite and each was also associated with higher delivery forces. CaPcomposites prepared with 10% high molecular weight CMC and hydrated athydrant to powder ratios of 0.5 to 0.6 mL/g did not exhibit anydispersion or leakage issues and were easily injected with the standarddelivery devices.

Example 13

Vertebroplasty involves injecting the bone cement of the presentinvention into small holes in weakened vertebrae to strengthen thespinal bones making them less likely to fracture again and providingpain relief. Using image-guidance, a hollow needle called a trocar ispassed through the skin into the spinal bone and the bone cement of thepresent invention is then injected into the vertebra.

Kyphoplasty is a minimally invasive spinal surgery procedure used totreat painful, progressive vertebral compression fractures (VCFs). A VCFis a fracture in the body of a vertebra, which causes it to collapse. Inturn, this causes the spinal column above it to develop an abnormalforward curve. VCFs may be caused by osteoporosis (an age-relatedsoftening of the bones) or by the spread of tumor to the vertebral body.Certain forms of cancer can also weaken bone and cause the sameproblems.

In kyphoplasty, a balloon is first inserted through the tube and intothe vertebral body of a fractured vertebra where it is inflated torestore the height and shape of the vertebral body. The balloon is thenremoved. This is followed by injection of a bone cement of the presentinvention into the cavity formed by the balloon to strengthen thevertebra. The procedure may be performed with the patient lying facedown on the operating room table and under intravenous sedation. X-raymachines (e.g., one, two, or more used together) can be used to show thecollapsed bones. The surgeon makes two small (less than 3 mm) incisionsin the back. A tube is inserted into the center of the vertebral body tothe site of the fractured bone. The balloon tamp is then inserted downthe tube and inflated. This pushes the bone back to its normal heightand shape. Inflation of the balloon creates a cavity in the vertebralbody, which the surgeon fills with the bone cement of the presentinvention. When the cement hardens, the tubes are removed. The incisionscan be closed with surgical stitches.

It is recommended that kyphoplasty be performed soon after a VCF happensto best restore vertebral body height and size. After kyphoplasty,severe osteoporosis may cause other fractures at other levels of thespine. Patients can also take bone-strengthening medications duringtreatment. If more vertebrae collapse, kyphoplasty in conjunction withthe bone cement of the present invention can be used at those otherlevels. Kyphoplasty tends to help prevent additional fractures bykeeping the spine aligned in its native upright position.

OTHER EMBODIMENTS

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure that come within known or customary practice withinthe art to which the invention pertains and may be applied to theessential features hereinbefore set forth.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindependent publication or patent application was specifically andindividually indicated to be incorporated by reference in theirentirety.

What is claimed is:
 1. A method for performing vertebroplasty on avertebral body comprising: a) injecting a flowable bone cement into atleast one said vertebral body, said flowable bone cement comprising ananocrystalline apatitic calcium phosphate, a radio-opaque agent,carboxymethyl cellulose in an amount of 10% or less by weight, and apharmaceutically acceptable fluid in an amount sufficient to producesaid flowable bone cement; and b) allowing said flowable bone cement toharden, wherein said flowable bone cement, when hardened, has acompressive strength of 1 mPa or greater and is resorbable in vivo. 2.The method of claim 1, wherein said flowable bone cement furthercomprises: a) at least one agent that promotes bone growth or inhibitsbone resorption; b) one or more crystal growth inhibitors; c)demineralized bone matrix; d) benzoyl peroxide powder; e) hydroxyethylmethacrylate (HEMA); f) a cohesiveness agent, an osteopenic agent, or amedicinal agent; or q) a biologically active agent.
 3. (canceled)
 4. Themethod of claim 1, wherein the pharmaceutically acceptable fluid isselected from water, saline, a phosphate buffer, a biological fluid, inparticular, blood or a fluid that includes blood components, andglycerol.
 5. The method of claim 1, wherein said vertebral body: a) isin a human or non-human mammal; or b) comprises fractured orosteoporotic bone.
 6. (canceled)
 7. The method of claim 1 furthercomprising: a) injecting said flowable bone cement into two or morevertebral bodies; or b) creating a cavity in said vertebral body andinjecting said flowable bone cement into said cavity.
 8. (canceled) 9.The method of claim 1, wherein said nanocrystalline apatitic calciumphosphate comprises crystals within the range of 30-80 nm, optionallywherein said nanocrystalline apatitic calcium phosphate comprisescrystals within the range of 30-50 nm.
 10. (canceled)
 11. The method ofclaim 1, wherein said nanocrystalline apatitic calcium phosphate: a) hasa crystallinity index value of less than 60% relative to hydroxyapatite;or b) is selected from amorphous calcium phosphate, poorly crystallinecalcium phosphate, hydroxyapatite, carbonated apatite (calcium-deficienthydroxyapatite), monocalcium phosphate, calcium metaphosphate,heptacalcium phosphate, dicalcium phosphate dihydrate, tetracalciumphosphate, octacalcium phosphate, calcium pyrophosphate, and tricalciumphosphate, or mixtures thereof. 12-17. (canceled)
 18. The method ofclaim 2, wherein said cohesiveness agent is selected from the groupconsisting of: a) one or more polymers selected from polysaccharides,nucleic acids, carbohydrates, proteins, polypeptides, poly(α-hydroxyacids), poly(lactones), poly(amino acids), poly(anhydrides),poly(orthoesters), poly(anhydride-co-imides), poly(orthocarbonates),poly(α-hydroxy alkanoates), poly(dioxanones), poly(phosphoesters),poly(L-lactide) (PLLA), poly(D,L-lactide) (PDLLA), polyglycolide (PGA),poly(lactide-co-glycolide (PLGA), poly(L-lactide-co-D, L-lactide),poly(D,L-lactide-co-trimethylene carbonate), polyhydroxybutyrate (PHB),poly(ε-caprolactone), poly(δ-valerolactone), poly(γ-butyrolactone),poly(caprolactone), polyacrylic acid, polycarboxylic acid,poly(allylamine hydrochloride), poly(diallyldimethylammonium chloride),poly(ethyleneimine), polypropylene fumarate, polyvinyl alcohol,polyvinylpyrrolidone, polyethylene, polymethylmethacrylate, carbonfibers, poly(ethylene glycol), poly(ethylene oxide), poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof; b) a homo- orco-polymer having one or more monomers selected from the groupconsisting of acrolein potassium, (meth)acrylamides, (meth)acrylic acidand salts thereof, (meth)acrylates, acrylonitrile, ethylene, ethyleneglycol, ethyleneimine, ethyleneoxide, styrene sulfonate, vinyl acetate,vinyl alcohol, vinyl chloride, and vinylpyrrolidone); c) a polyphenoliccomplexing agent selected from gallotannins, ellagitannins,taragallotannins, caffetannins, proanthocyanidins, catechin,epicatechin, chlorogenic acid, and arbutin; and d) an agent selectedfrom alginic acid, arabic gum, guar gum, xantham gum, gelatin, chitin,chitosan, chitosan acetate, chitosan lactate, chondroitin sulfate,N,O-carboxymethyl chitosan, a dextran, fibrin glue, glycerol, hyaluronicacid, sodium hyaluronate, a cellulose, in particular, carboxymethylcellulose, a glucosamine, a proteoglycan, a starch, lactic acid, apluronic, sodium glycerophosphate, collagen, glycogen, a keratin, silk,and mixtures thereof; said osteogenic agent is selected from the groupconsisting of transforming growth factors-beta (TGF-β), activins,inhibins, and bone morphogenetic proteins (BMPs); said medicinal agentis selected from the group consisting of antibiotics, enzyme inhibitors,antihistamines, anti-inflammatory agents, muscle relaxants,anti-spasmodics, analgesics, prostaglandins, anti-depressants, trophicfactors, and hormones; and said biologically active agent is selectedfrom the group consisting of organic molecules, inorganic materials,proteins, peptides, nucleic acids, nucleoproteins, polysaccharides,glycoproteins, lipoproteins, antibodies, growth factors, and anti-canceragents. 19-20. (canceled)
 21. The method of claim 1, comprisinginjecting said flowable bone cement into said vertebral body using aneedle having a size of 16 gauge or less, optionally wherein the needleis an 11 gauge needle. 22-45. (canceled)
 46. A method of preparing abone cement comprising admixing a calcium phosphate material comprisingcrystals within the range of 30-80 nm, a radio-opaque agent, andcarboxymethyl cellulose in an amount of 10% or less by weight.
 47. Themethod of claim 46, wherein: a) the method comprises high energygrinding the calcium phosphate material prior to said admixing; or b)the radio-opaque agent is selected from the group consisting of barium,iodine, lanthanum oxide, zirconium oxide, and sodium alginate,optionally wherein the barium is barium carbonate, barium sulfate, orbarium apatite; or the iodine is methyl methacrylate,2-(2-iodobenzoyl)-ethyl methacrylate, Renografin-60, or ISOVUE.
 48. Themethod of claim 46, wherein the calcium phosphate material: a) comprisesa nanocrystalline apatite or nano-low crystalline apatite; b) has acalcium to phosphate ratio (Ca/P) of less than 1.67; c) comprisesamorphous calcium phosphate and dicalcium phosphate dihydrate; d)comprises crystals within the range of 30-50 nm; e) has a crystallinityindex value of less than 60% relative to hydroxyapatite; or f) isselected from amorphous calcium phosphate, poorly crystalline calciumphosphate, hydroxyapatite, carbonated apatite (calcium-deficienthydroxyapatite), monocalcium phosphate, calcium metaphosphate,heptacalcium phosphate, dicalcium phosphate dihydrate, tetracalciumphosphate, octacalcium phosphate, calcium pyrophosphate, and tricalciumphosphate, or mixtures thereof.
 49. The method of claim 46, wherein themethod further comprises: a) admixing a pharmaceutically acceptablefluid with the bone cement to produce a flowable bone cement, optionallywherein the pharmaceutically acceptable fluid is selected from the groupconsisting of water, saline, a phosphate buffer, a biological fluid, inparticular, blood or a fluid that includes blood components, andglycerol; b) admixing at least one agent that promotes bone growth orinhibits bone resorption with the bone cement; c) admixing one or morecrystal growth inhibitors with the bone cement; d) admixingdemineralized bone matrix with the bone cement; e) admixing benzoylperoxide powder with the bone cement; f) admixing hydroxyethylmethacrylate (HEMA with the bone cement); or g) admixing a supplementalmaterial selected from the group consisting of a cohesiveness agent, anosteogenic agent, a biologically active agent, and a medicinal agentwith the bone cement.
 50. The method of claim 49, wherein the methodfurther comprises loading the flowable bone cement into a deliverysyringe configured for vertebral injection.
 51. The method of claim 49,wherein the flowable bone cement: a) is formulated for injection; b) isformulated as a formable material or paste; c) hardens in less than 1hour at 37° C.; d) has a compressive strength of 1 MPa after hardening;or e) is resorbable in vivo.
 52. The method of claim 51, wherein saidflowable bone cement is capable of being injected through a needlehaving a size of 16 gauge or less, optionally wherein said needle is an11 gauge needle.
 53. The method of claim 49, wherein said cohesivenessagent is selected from the group consisting of: a) one or more polymersselected from the group consisting of polysaccharides, nucleic acids,carbohydrates, proteins, polypeptides, poly(α-hydroxy acids),poly(lactones), poly(amino acids), poly(anhydrides), poly(orthoesters),poly(anhydride-co-imides), poly(orthocarbonates), poly(α-hydroxyalkanoates), poly(dioxanones), poly(phosphoesters), poly(L-lactide)(PLLA), poly(D,L-lactide) (PDLLA), polyglycolide (PGA),poly(lactide-co-glycolide (PLGA), poly(L-lactide-co-D, L-lactide),poly(D,L-lactide-co-trimethylene carbonate), polyhydroxybutyrate (PHB),poly(ε-caprolactone), poly(δ-valerolactone), poly(γ-butyrolactone),poly(caprolactone), polyacrylic acid, polycarboxylic acid,poly(allylamine hydrochloride), poly(diallyldimethylammonium chloride),poly(ethyleneimine), polypropylene fumarate, polyvinyl alcohol,polyvinylpyrrolidone, polyethylene, polymethylmethacrylate, carbonfibers, poly(ethylene glycol), poly(ethylene oxide), poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyloxazoline), poly(ethyleneoxide)-co-poly(propylene oxide) block copolymers, poly(ethyleneterephthalate)polyamide, and copolymers thereof; b) a homo- orco-polymer having one or more monomers selected from the groupconsisting of acrolein potassium, (meth)acrylamides, (meth)acrylic acidand salts thereof, (meth)acrylates, acrylonitrile, ethylene, ethyleneglycol, ethyleneimine, ethyleneoxide, styrene sulfonate, vinyl acetate,vinyl alcohol, vinyl chloride, and vinylpyrrolidone; c) a polyphenoliccomplexing agent selected from the group consisting of gallotannins,ellagitannins, taragallotannins, caffetannins, proanthocyanidins,catechin, epicatechin, chlorogenic acid, and arbutin; and d) an agentselected from the group consisting of alginic acid, arabic gum, guargum, xantham gum, gelatin, chitin, chitosan, chitosan acetate, chitosanlactate, chondroitin sulfate, N,O-carboxymethyl chitosan, a dextran,fibrin glue, glycerol, hyaluronic acid, sodium hyaluronate, and acellulose, in particular, carboxymethyl cellulose, a glucosamine, aproteoglycan, a starch, lactic acid, a pluronic, sodiumglycerophosphate, collagen, glycogen, a keratin, silk, and mixturesthereof; said osteogenic agent is selected from the group consisting oftransforming growth factors-beta (TGF-β), activins, inhibins, and bonemorphogenetic proteins (BMPs); said medicinal agent is selected from thegroup consisting of antibiotics, enzyme inhibitors, antihistamines,anti-inflammatory agents, muscle relaxants, anti-spasmodics, analgesics,prostaglandins, anti-depressants, trophic factors, and hormones; andsaid biologically active agent is selected from the group consisting oforganic molecules, inorganic materials, proteins, peptides, nucleicacids, nucleoproteins, polysaccharides, glycoproteins, lipoproteins,antibodies, growth factors, and anti-cancer agents.
 54. A bone cementpowder comprising a calcium phosphate material comprising crystalswithin the range of 30-80 nm, a radio-opaque agent, and carboxymethylcellulose in an amount of 10% or less by weight, optionally wherein saidcalcium phosphate material comprises one or more of poorly crystallinecalcium phosphate, amorphous calcium phosphate, and dicalcium phosphatedihydrate.
 55. The bone cement powder of claim 55, wherein theradio-opaque agent is selected from the group consisting of barium,iodine, lanthanum oxide, zirconium oxide, and sodium alginate,optionally wherein the barium is barium carbonate, barium sulfate, orbarium apatite; or the iodine is methyl methacrylate,2-(2-iodobenzoyl)-ethyl methacrylate, Renografin-60, or ISOVUE.
 56. Akit comprising the bone cement powder of claim 54.